Combine power selection system

ABSTRACT

A system for propelling a combine over the ground and driving other components of the combine includes an engine driving a transmission via a hydrostatic drive system. A microprocessor stores a work table and a road table for controlling engine speed. A gear selector operates a switch to select one of the tables and a throttle control operates switches to select a speed value from the selected table. When working a field, the work table is selected so that the engine runs at speeds in a range suitable for driving the other components. For transport of the combine the road table is selected so that the engine may run at a speed higher than speeds suitable for driving the other components. For a given setting of the throttle control, the engine is controlled to run at either a first or second speed depending on the setting of the gear select lever.

FIELD OF THE INVENTION

[0001] The present invention relates to an engine speed control systemfor a combine harvester having a hydrostatic wheel drive system forpropelling the combine over the ground. More particularly, the inventionprovides for alternate engine speeds for a single setting of a throttlecontrol member.

BACKGROUND OF THE INVENTION

[0002] Some combines employ a hydrostatic drive system wherein aninternal combustion engine drives a hydrostatic pump. The pump drives ahydrostatic motor, the motor in turn driving the wheels of the combinethrough a transmission to propel the combine over the ground. Hydraulicflow from the pump to the hydrostatic motor is governed by thedisplacement of the hydrostatic pump and the speed at which the pump isdriven by the engine. Typically, the engine also provides power tooperate other components of the combine such as the header, threshingunit and unload tube conveyor and positioning unit. The power fordriving these components is obtained by a power take-off from the engineor by hydraulic flow from the hydrostatic pump.

[0003] For reasons of fuel economy and to prevent overload of thecomponents when they are being driven, the speed of the engine islimited so that only enough power to satisfy the requirements of thecomponents is made available to them. This limits the maximum groundspeed normally obtainable. When the engine speed is so limited, themaximum ground speed of the combine is less than one might desire whenthe combine is traveling along a roadway.

SUMMARY OF THE INVENTION

[0004] An object of the present invention is to provide an engine speedcontrol system for a combine harvester, the control system avoidingpower overload of harvester components and yielding fuel efficiency whenharvesting a crop, and permitting higher engine speeds for propellingthe harvester on a roadway.

[0005] Another object of the invention is to provide an engine speedcontrol system for a combine harvester, the system being responsive to amanually actuated throttle control to cause the engine to run at eithera first or work speed, or a second or road speed, for at least onesetting of the throttle control, the road speed being greater than thework speed.

[0006] A further object of the invention is to provide an engine speedcontrol system for a combine harvester, the system being responsive to amanually actuated multi-state throttle control to cause the engine torun at either a first or work speed or a second or road speed for eachstate of the throttle control, the road speed for each state of thethrottle control being greater than the work speed for the same state ofthe throttle control.

[0007] Yet another object of the invention is to provide a combineharvester having wheels for propelling the combine harvester over theground; an engine driving the wheels via a hydrostatic drive system; amanually operable throttle control including a lever selectivelysettable to any one of a plurality of positions, each positioncorresponding to a desired engine speed; a speed modification switchhaving a first state and a second state; and an engine control circuitfor controlling the speed of said engine, the engine control circuitbeing responsive to the position of the throttle control lever and thespeed modification switch for selectively controlling the engine to runat a first speed for a given position of the throttle control lever whenthe speed modification switch is in the first state and to run at asecond speed higher than the first speed when the throttle control leveris in the given position and the speed modification switch is in thesecond state.

[0008] Another object of the invention is to provide a combine harvesteras described above wherein the engine speed control circuit comprises aprogrammable microprocessor having means for storing a first tableholding work speed values, one work speed value corresponding to eachposition of a throttle control lever, and a second table holding atleast one road speed value greater than any of the work speed values;means for accessing a work speed value from the first table when a speedmodification switch is in a first state and accessing a road speed valuefrom the second table when the speed modification switch is in a secondstate; and means responsive to an accessed a work speed value oraccessed road speed value for producing an output signal to control theengine to run at the speed represented by the accessed work speed orroad speed value. The output signal from the microprocessor controls theengine speed by controlling the rate of fuel flow to the engine.

[0009] In a preferred embodiment, the table of road speed valuesincludes a road speed value corresponding to each position of thethrottle control lever, the road speed value corresponding to a givenposition of the throttle control lever being greater than the work speedvalue corresponding to the given position of the throttle control leverwhereby, for each position of the throttle control lever, the engine maybe selectively controlled to run at a first speed or a second speedhigher than the first speed, depending on the state of the speedmodification switch.

[0010] In addition to permitting a high range of road speeds, theinvention also has the advantage that it permits a change in road speedwithout shifting gears.

[0011] Other objects and advantages of the invention will become obviousfrom consideration of the following description and the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012]FIG. 1 is a side view of a combine harvester in which the presentinvention may be implemented;

[0013]FIG. 2 schematically illustrates an engine speed control systemfor a combine, the engine driving wheels of the combine via ahydrostatic drive system; and,

[0014]FIG. 3 is a flow chart illustrating a microprocessor program forsetting the engine speed at either one of two speeds for each positionof a throttle control lever.

DETAILED DESCRIPTION OF THE INVENTION

[0015]FIG. 1 illustrates a typical twin rotor combine in which thepresent invention may be used. The combine 1 includes a header 3 havinga reel 4 for cutting crop as the combine moves forwardly over a cropfield. Crop material (grain and stalks) cut by reel 4 is fed to atransverse rotating auger 8 that moves the crop material toward thecenter of the header. From auger 8, the crop material is picked up by aconveyor 11 and fed to a threshing, separation and cleaning system 6that separates the stalk material and chaff from the grain. Theprocessed grain is stored in a grain tank 5 positioned near the top ofthe combine and the stalk material is discharged from the rear of thecombine. The grain is removed from the grain tank by an unloading auger(not shown) through a grain tank unload tube 7. The unload tube 7 ispivotally mounted so that it may swing outwardly, thus permitting thedischarge of processed grain into a truck or cart (not shown) movingalong side the combine.

[0016] Referring to FIG. 2, power for driving the wheels 10 of combine 1is derived from an internal combustion engine 20. The engine drives ahydrostatic drive system 22 that includes a hydrostatic pump 24 and ahydrostatic motor 26. Engine 20 drives hydrostatic pump 24 via afluid/mechanical coupling 28. The resulting fluid flow from pump 24drives motor 26 via fluid conduits 30. As the motor 26 rotates, itdrives the input shaft 32 of a transmission 34 that in turn transmitsdrive power to wheels 10.

[0017] The flow from pump 24 is determined by its displacement and inputspeed with the input speed being in direct ratio to the speed (rate ofrotation) of the output shaft 36 of engine 20.

[0018] Operator 14 (FIG. 1) manually operates a throttle control 38 toselect a speed at which engine 20 runs. The throttle control preferablyincludes a plurality of throttle control switches 40 operated by a lever42 as it is set to one of several lever positions. However, the throttlecontrol may take other forms such as a control panel having pushbuttonsactuated by the operator to set the throttle control to one of multiplestates. As explained below, the throttle control 38 does not determinethe desired speed of engine 20 but merely selects a speed level within afirst or second range of speed levels, the first or second range beingdetermined by the positioning of a gear shift lever 50.

[0019] An engine control circuit or programmable microprocessor 44periodically senses the state of the throttle control switches 40 and aswitch 54 operated by the gear shift lever 50, and controls engine 20 torun at a desired speed. The microprocessor 44 also periodically samplesthe output of an engine speed sensor 46. As subsequently describedmicroprocessor 44 compares the sensed or actual engine speed with thedesired speed. If the sensed engine speed is less than the desiredspeed, the microprocessor 44 produces an output signal to increase therate of fuel flow to the engine 20 to thereby increase its speed to thedesired speed. Control of the rate of fuel flow is accomplished in aconventional manner, and may, for example, be done by controlling fuelinjectors.

[0020] Engine 20, in addition to providing power to drive wheels 10,also provides power for actuating or driving other components of thecombine such as the header 3, unload tube 7, and threshing, separationand cleaning system 6. The power for these components may be obtaineddirectly from engine 20 via a power take-off (PTO) 48 and/orhydraulically from hydrostatic pump 24. Although the other componentsare not driven from the PTO during times when the combine is beingtransported, the engine speed, typically, has been selectable from arange of engine speeds that provide fuel economy and best accommodatethe power and speed requirements of these components. These speedsresult in ground speeds that are relatively slow, or at least slowerthan desired when the combine is being transported (driven) on a roadwayor from one field to another.

[0021] Transmission 34 is provided with a gear select lever 50 forchanging the gear ratio between the input shaft 32 and output shaft 52of the transmission. In actual practice, and for reasons not relating tothe present invention, lever 50 is movable between three activepositions and a default position and in each position actuates a switch.However, to simplify explanation of the present invention it will beassumed that lever 50 is movable between only a HI position in which itcloses a two-state speed modification switch 54 and a LO position inwhich switch 54 is open.

[0022] Switch 54 is connected to the microprocessor 44 and modifies theoperation of the microprocessor program so that, for any given settingof throttle control switches 40, the engine 20 is controlled to run at anormal or work speed when the switch is in a first state (open), or ahigher or road speed when the switch is in a second state (closed).

[0023]FIG. 3 shows a portion of the microprocessor program executed byengine control microprocessor 44 to set the speed of engine 20. It willbe understood that the portion shown in FIG. 3 comprises part of alarger program that is periodically repeated at some time interval, say32.77 ms.

[0024] At step 60 the microprocessor senses the throttle switches 40 toobtain an indication of what speed level has been selected by theoperator via throttle lever 42. At step 62 the microprocessor senses thestate of switch 54.

[0025] The microprocessor includes in a non-volatile memory (notseparately shown) that stores two tables of speed values. A Work Speedtable stores a work speed value corresponding to each position of thethrottle lever 42. This table is accessed to obtain speed values forcontrolling engine 20 when working or harvesting a field.

[0026] The second table is a Road Speed table and it also holds a roadspeed value for each position of lever 42. The road speed values areused if switch 54 is closed to control the speed of the engine 20 duringtransport, that is, when the combine is traveling on a roadway or movingfrom one field to another. For any given position of lever 42, the speedvalue in the Road Speed table is greater than the speed value in theWork Speed table.

[0027] The speed values store in the Road Speed and Work Speed tablesare digital values which, when converted to analog output signals by themicroprocessor and applied to the fuel control of engine 20, cause theengine to run at the designated speeds.

[0028] If step 62 determines that speed modification switch 54 is notclosed, the table of work speed values is accessed at step 64 using thethrottle lever position sensed at step 60. That is, switch 54 serves asthe base address of the Work Speed table and the output signal from thethrottle switches 40 addresses a specific location in the table. On theother hand, when step 62 determines that the speed modification switch54 is closed, the table of road speed values is accessed at step 68using the lever position sensed at step 60.

[0029] After either a work speed or a road speed value is obtained, step66 samples the output of sensor 46 to determine the current speed ofengine 20. Step 70 then compares the sensed engine speed with the workspeed value obtained from memory at step 64 or the road speed valueobtained at step 68. If the sensed engine speed is less than the valueobtained from memory, step 72 is executed to develop an output signalthat is applied to the fuel control of engine 26 to cause the engine toincrease speed to the speed value retrieved at step 64 or 68.

[0030] Step 72 is bypassed when step 70 determines that the sensedengine speed is not less than the value obtained from memory at step 64or 68.

[0031] From the foregoing description it is evident that the presentinvention provides an inexpensive means for solving the problem ofundesirably slow road speeds. The only additional hardware that isrequired is the switch 54. Advantageously, the invention permits anoperator to change the ground speed of the combine without effecting achange in the gear ratio in the transmission 34. The ground speed may bechanged merely by moving lever 42 so as to change the output signalsproduced by switches 40. It will also be evident that the systemprovides an instant response to load fluctuations in the field. Anychange in engine speed is immediately sensed by sensor 46 and themicroprocessor modifies it output signal to engine 20 to compensate forthe change.

[0032] Although a preferred embodiment has been described in detail toillustrate the principles of the invention, various modifications arepossible. For example, it is not necessary for the Road Speed table tohold road speed values corresponding to every position of lever 50.Instead, the Road Speed table may hold only one road speed valuecorresponding to one position (highest speed position) of the lever. Inthis case the program illustrated in FIG. 3 must be modified to provide,between steps 60 and 62, a further step for determining if the selectedspeed detected at step 60 is the highest speed. If it is not, theprogram would advance directly to step 64 but if the highest speed isselected then step 62 would be executed to determine the state of switch54.

[0033] Other modifications and substitutions may be made in thedescribed embodiment without departing from the spirit and scope of theinvention as defined by the appended claims.

I claim:
 1. A combine harvester having: wheels for propelling thecombine harvester over the ground; an engine driving said wheels via ahydrostatic drive system; a manually operable throttle control having aplurality of positions, each position corresponding to a desired enginespeed level; a speed modification switch having a first state and asecond state; and, an engine control circuit for controlling the speedof said engine; said engine control circuit being responsive to saidthrottle control and said speed modification switch for selectivelycontrolling said engine to run at a first speed for a given position ofsaid throttle control when said speed modification switch is in saidfirst state and to run at a second speed higher than said first speedwhen said throttle control is in said given position and said speedmodification switch is in said second state.
 2. A combine harvester asclaimed in claim 1 wherein said engine control circuit comprises aprogrammable microprocessor.
 3. A combine harvester as claimed in claim1 wherein said engine control circuit comprises a programmablemicroprocessor having: means for storing a first table holding workspeed values, one work speed value corresponding to each position ofsaid throttle control, and a second table holding at least one roadspeed value greater than any of said work speed values; means foraccessing a work speed value from said first table when said speedmodification switch is in said first state and accessing a road speedvalue from said second table when said speed modification switch is insaid second state; and, means responsive to an accessed a work speedvalue or road speed value for producing an output signal to control saidengine to run at the speed represented by said accessed work speed valueor accessed road speed value.
 4. A combine harvester as claimed in claim3 wherein said table of road speed values includes a road speed valuecorresponding to each position of said throttle control, the road speedvalue corresponding to a given position of said throttle control beinggreater than the work speed value corresponding to said given positionof said throttle control whereby, for each position of said throttlecontrol, said engine may be selectively controlled to run at a firstspeed or a second speed higher than said first speed, depending on thestate of said speed modification switch.
 5. A combine harvester asclaimed in claim 3 wherein said output signal controls the rate of fuelflow to said engine.
 6. A combine harvester as claimed in 3, furthercomprising other harvester components including, a threshing, cleaningand separation system powered by said engine, said work speed valuesbeing chosen so the output power of said engine does not overload saidother harvester components.